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Fix uart time precision problem

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This commit is contained in:
Florian Zaruba 2018-10-25 14:57:15 +02:00
parent 26fde6e49e
commit 23b7740d74
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GPG key ID: E742FFE8EC38A792
1 changed files with 18 additions and 29 deletions
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47
tb/common/uart.sv
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@ -14,15 +14,15 @@
// A string is printed to the console as soon as a '\n' character is found
interface uart_bus #(
parameter BAUD_RATE = 115200,
parameter PARITY_EN = 0
parameter int unsigned BAUD_RATE = 115200,
parameter int unsigned PARITY_EN = 0
)(
input logic rx,
output logic tx,
input logic rx_en
);
localparam BIT_PERIOD = (1000000000/BAUD_RATE*1000);
localparam time BIT_PERIOD = (1000000000 / BAUD_RATE) * 1ns;
logic [7:0] character;
logic [256*8-1:0] stringa;
@ -30,35 +30,28 @@ interface uart_bus #(
integer charnum;
integer file;
initial
begin
initial begin
tx = 1'bZ;
file = $fopen("stdout/uart", "w");
end
always
begin
if (rx_en)
begin
always begin
if (rx_en) begin
@(negedge rx);
#(BIT_PERIOD/2) ;
for (int i=0;i<=7;i++)
begin
#(BIT_PERIOD/2);
for (int i = 0; i <= 7; i++) begin
#BIT_PERIOD character[i] = rx;
end
if(PARITY_EN == 1)
begin
if (PARITY_EN == 1) begin
// check parity
#BIT_PERIOD parity = rx;
for (int i=7;i>=0;i--)
begin
for (int i=7;i>=0;i--) begin
parity = character[i] ^ parity;
end
if(parity == 1'b1)
begin
if (parity == 1'b1) begin
$display("Parity error detected");
end
end
@ -68,24 +61,20 @@ interface uart_bus #(
$fwrite(file, "%c", character);
stringa[(255-charnum)*8 +: 8] = character;
if (character == 8'h0A || charnum == 254) // line feed or max. chars reached
begin
if (character == 8'h0A)
if (character == 8'h0A || charnum == 254) begin // line feed or max. chars reached
if (character == 8'h0A) begin
stringa[(255-charnum)*8 +: 8] = 8'h0; // null terminate string, replace line feed
else
end else begin
stringa[(255-charnum-1)*8 +: 8] = 8'h0; // null terminate string
end
$write("RX string: %s\n",stringa);
$write("[UART]: %s\n", stringa);
charnum = 0;
stringa = "";
end
else
begin
end else begin
charnum = charnum + 1;
end
end
else
begin
end else begin
charnum = 0;
stringa = "";
#10;